Spray AnyParam with default value Bug

AnyParamSpec.scala

import org.specs2.mutable.Specification
import spray.http._
import spray.routing._
import spray.testkit.Specs2RouteTest

class AnyParamSpec extends Specification with Specs2RouteTest with Directives {
  
  val route = anyParam('p ? "default") { p => complete(StatusCodes.OK, p) } 
  // replace with the following workaround
  //val route = (anyParam('p) | provide("default")) { p => complete(StatusCodes.OK, p) } 
  
  "anyParam with default value should check form fields and query parameters before applying default value" >> {
    
    "request with explicit form field" in {
      Post("/", FormData(Seq("p" -> "specified"))) ~> route ~> check {
        responseAs[String] must_== "specified"
      }
    }
    
    "request with explicit query param" in {
      Get("/?p=specified") ~> route ~> check {
        responseAs[String] must_== "specified"
      }
    }
    
    "request with no param" in {
      Get("/") ~> route ~> check {
        responseAs[String] must_== "default"
      }
    }
  }
 
}

build.sbt

scalaVersion := "2.11.4"

scalaSource in Test := baseDirectory.value

libraryDependencies ++= Seq(
  "io.spray" %% "spray-routing-shapeless2" % "1.3.2",
  "io.spray" %% "spray-testkit" % "1.3.2",
  "org.specs2" %% "specs2" % "2.4.10"
)